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Leetcode - Read N Characters Given Read4

 
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The API: int read4(char *buf) reads 4 characters at a time from a file.

The return value is the actual number of characters read. For example, it returns 3 if there is only 3 characters left in the file.

By using the read4 API, implement the function int read(char *buf, int n) that reads n characters from the file.

Note:
The read function will only be called once for each test case.

[分析]
有同学说这题题意不明,深有同感,如果题目明确说明read4是从file中读4个字符到buf,而要求实现的read是通过调用read4从file中读取n个字符到buf并返回实际读取的字符数就比较清楚啦
https://leetcode.com/discuss/19573/accepted-clean-java-solution

/* The read4 API is defined in the parent class Reader4.
      int read4(char[] buf); */

public class Solution extends Reader4 {
    /**
     * @param buf Destination buffer
     * @param n   Maximum number of characters to read
     * @return    The number of characters read
     */
    public int read(char[] buf, int n) {
        char[] buffer = new char[4];
        int readBytes = 0;
        boolean eof = false;
        while (readBytes < n && !eof) {
            int currRead = read4(buffer);
            if (currRead < 4)
                eof = true;
            int minLen = Math.min(currRead, n - readBytes);
            for (int i = 0; i < minLen; i++) {
                buf[readBytes + i] = buffer[i];
            }
            readBytes += minLen;
        }
        return readBytes;
    }
}
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